I understand that she said he was the love of her life, but she herself has moved on and has a significant other. I believe people can be the “love of your life” but still not mean you are good together as a couple. They have known eachother for something like 30 years, were married and lived together for many of those years & have children together. They definitely had a very deep connection.
The whole family knows about B (it was on tv & written about in tabloids) and have for years. In my opinion I think she has the right to attend the funeral. Sit with the family no, but attend if she wants.
Many people now aren’t divorcing and just separating for financial reasons (taxes, medical insurance, assets etc.). If it works for the people involved, I don’t see the problem with it.